JP7620440B2 - Autonomous Driving Assistance System - Google Patents

Description

The present invention relates to an automated driving assistance system that changes the upper limit of vehicle speed to suppress sudden deceleration control on roads with multiple closely spaced intersections.

When the driver (operator) sets a destination, the autonomous driving assistance system sets a driving route from the current location to the destination and automatically drives the vehicle along all or part of that route on behalf of the driver. When driving autonomously on public roads, this autonomous driving assistance system recognizes the driving environment ahead of the vehicle using sensing devices such as cameras, and constantly monitors the presence or absence of preceding vehicles, the color of traffic lights, the direction indicated by arrow signal lights, etc.

If a preceding vehicle is detected on the target driving route ahead of the vehicle, the adaptive cruise control (ACC) function equipped in the autonomous driving assistance system is activated, and the vehicle's speed is controlled to a predetermined speed based on the distance to the preceding vehicle, relative vehicle speed, etc. This ACC function also recognizes the color of the traffic lights installed at the intersection based on forward environmental information obtained from an on-board camera, etc., and when the color of the traffic lights is green (green light), the vehicle travels at the ACC set vehicle speed set by the driver, with the road's speed limit as the upper limit.

As an example of such an automated driving assistance system, Patent Document 1 discloses a driving assistance device that varies the assistance mode (assistance level) to be provided depending on the status of each traffic light when there are consecutive intersections with traffic lights.

JP 2011-221757 A

In a scenario where the vehicle is traveling straight on a road with two successive intersections with traffic lights, if the automated driving assistance system determines that the traffic light at the upcoming intersection is green based on information about the driving environment ahead obtained from an in-vehicle camera or the like, it will pass through the upcoming intersection at the ACC set vehicle speed. After that, when the automated driving assistance system recognizes that the traffic light at the intersection further back is red, it will perform deceleration control to stop the vehicle before the stop line at the intersection further back.

However, when the distance between two intersections is short, the autonomous driving assistance system must suddenly decelerate the vehicle unintentionally in order to stop at an intersection where the light is red, resulting in a deterioration of the ride comfort for passengers.

The present invention was made in consideration of the above circumstances, and aims to provide an automated driving assistance system that can suppress sudden deceleration control that is not intended by the driver.

An autonomous driving assistance system according to one embodiment of the present invention is an autonomous driving assistance system that acquires the driving environment of a predetermined range of a target route ahead of the host vehicle based on road map information acquired by a road map information acquisition unit and driving environment information ahead of the host vehicle acquired by a camera unit, and has an intersection detection unit that detects a set of intersections whose interval is shorter than a predetermined interval within the predetermined range of the target route ahead of the host vehicle based on the driving environment of the predetermined range of the target route, and an ACC set vehicle speed change unit that changes a set first ACC set vehicle speed to a second ACC set vehicle speed that is slower than the first ACC set vehicle speed when the intersection detection unit detects a set of intersections whose interval is shorter than the predetermined interval, and the intersection detection unit detects whether there is a set of intersections whose interval is shorter than the driving distance that the host vehicle, while traveling at the first ACC set vehicle speed, travels until it continues to decelerate at a preset upper limit of deceleration and stops .

The automated driving assistance system of the present invention can suppress sudden deceleration control that is not intended by the driver.

Schematic diagram of the autonomous driving assistance system An explanatory diagram of a road where the traffic lights at the intersection in front and the traffic lights at the intersection in the back are consecutive A flowchart showing an example of a process for controlling a change in the ACC set vehicle speed

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
In the drawings used in the following explanation, the scale of each component is different so that each component can be recognized on the drawing. The present invention is not limited to the quantity of components, the shapes of components, the size ratios of the components, and the positional relationships of each component shown in these drawings.

First, the general configuration of an automated driving assistance system according to one embodiment of the present invention will be described below with reference to the functional block diagram in FIG.

The automated driving assistance system 1 shown in FIG. 1 is mounted on the vehicle M (see FIG. 2). This automated driving assistance system 1 has a locator unit 11 as a means for detecting the position of the vehicle M (the vehicle's position), a camera unit 21 as a means for acquiring forward driving environment information, and a vehicle control unit 22 as a vehicle control means.

The locator unit 11 estimates the vehicle's position on a road map and acquires road map data around the vehicle's position. Meanwhile, the camera unit 21 acquires driving environment information ahead of the vehicle M, recognizing the lane markings dividing the left and right sides of the driving lane, the road shape, the presence or absence of a preceding vehicle, traffic lights, etc. Furthermore, the camera unit 21 determines the road curvature at the center of the lane markings, the distance between the vehicle and the preceding vehicle, the relative speed, etc.

The locator unit 11 has a map locator calculation unit 12 and a high-precision road map database (abbreviated as road map DB in FIG. 1) 16 as a storage means. The map locator calculation unit 12, the forward driving environment recognition unit 21d (described later), and the vehicle control unit 22 are composed of a well-known microcomputer equipped with a CPU, RAM, ROM, etc., and peripheral devices thereof, and the ROM stores programs to be executed by the CPU, fixed data such as base maps, etc.

The input side of the map locator calculation unit 12 is connected to a GNSS (Global Navigation Satellite System) receiver 13, an autonomous driving sensor 14, and a destination information input device 15. The GNSS receiver 13 receives positioning signals transmitted from multiple positioning satellites. The autonomous driving sensor 14 enables autonomous driving in environments where the reception sensitivity from the GNSS satellites is low and the positioning signals cannot be effectively received, such as driving inside a tunnel, and is composed of a vehicle speed sensor, a gyro sensor, a longitudinal acceleration sensor, and the like. The map locator calculation unit 12 determines the travel distance and direction based on the speed of the host vehicle M (host vehicle speed) detected by the vehicle speed sensor, the angular velocity detected by the gyro sensor, and the longitudinal acceleration detected by the longitudinal acceleration sensor, and performs localization based on the obtained travel distance and direction.

The destination information input device 15 is a terminal device operated by a person on board the vehicle, such as a driver or a passenger. This destination information input device 15 can collect and input a series of information required when setting a driving route in the map locator calculation unit 12, such as setting and inputting the destination and intermediate points (such as service areas on expressways).

The destination information input device 15 is specifically an input unit of a car navigation system (e.g., a touch panel of a monitor), a mobile terminal such as a smartphone, a personal computer, etc., and is connected to the map locator calculation unit 12 by wire or wirelessly.

When the driver or passenger operates the destination information input device 15 to input information about the destination or intermediate points (facility name, address, telephone number, etc.), this input information is read into the map locator calculation unit 12. The map locator calculation unit 12 then sets the position coordinates (latitude, longitude) for the input destination or intermediate point.

The map locator calculation unit 12 includes a vehicle position estimation calculation unit 12a as a vehicle position estimation means, a road map information acquisition unit 12b, and a target course setting calculation unit 12c as a target course setting means. The vehicle position estimation calculation unit 12a acquires position coordinates (latitude, longitude) that are position information of the vehicle M based on the positioning signal received by the GNSS receiver 13. In an environment where a valid positioning signal cannot be received from a positioning satellite due to a decrease in sensitivity of the GNSS receiver 13, the vehicle position estimation calculation unit 12a estimates the position coordinates of the vehicle M based on a signal from the autonomous driving sensor 14.

The road map information acquisition unit 12b performs map matching on the road map stored in the high-precision road map database 16 between the position coordinates of the vehicle M and the position coordinates (latitude, longitude) of the destination set by the destination information input device 15. The road map information acquisition unit 12b then identifies both positions and transmits road map information from the current vehicle position to the target route setting calculation unit 12c.

The high-precision road map database 16 is a large-capacity storage medium such as an HDD, and stores high-precision road map information (dynamic map). This high-precision road map information includes lane data (lane width data, lane center position coordinate data, lane travel azimuth data, speed limit, etc.) required for autonomous driving, and this lane data is stored at intervals of several meters for each lane on the road map.

The target path setting calculation unit 12c first creates a driving route on a road map connecting the current position and the destination, which have been map-matched by the road map information acquisition unit 12b. Next, the target path setting calculation unit 12c sequentially sets and updates a target path (straight ahead, turning right or left at an intersection, driving lanes such as the left lane, center lane, or right lane if going straight, and lateral position within the lane, etc.) for the vehicle M to travel automatically on this driving route, for a distance of several hundred to several kilometers ahead of the vehicle M. The information on this target path is read by the vehicle control unit 22.

On the other hand, the camera unit 21 is fixed to the upper center of the front part of the vehicle interior of the vehicle M, and has an on-board camera (stereo camera) consisting of a main camera 21a and a sub-camera 21b arranged at symmetrical positions on either side of the center in the vehicle width direction, an image processing unit (IPU) 21c, and a forward driving environment recognition unit 21d. This camera unit 21 processes the driving environment image information captured by both cameras 21a and 21b of a predetermined imaging area If (see Figure 2) in front of the vehicle M in a predetermined manner in the IPU 21c.

The forward driving environment recognition unit 21d reads the driving environment image information that has been image-processed by the IPU 21c, and recognizes the forward driving environment (forward driving environment information) based on this driving environment image information. The forward driving environment that is recognized includes the road shape (the road curvature [1/m] at the center of the dividing line dividing the left and right, and the width between the left and right dividing lines (vehicle width)) of the path along which the host vehicle M is traveling (host vehicle path), intersections, the lighting colors of traffic lights, road signs, pedestrians, bicycles, and other crossing persons, etc.

The vehicle control unit 22 also includes a vehicle control calculation unit 22a, an intersection detection unit 22b, and an ACC set vehicle speed change unit 22c, and the input side of the vehicle control unit 22 is connected to the target route setting calculation unit 12c of the map locator calculation unit 12, the forward driving environment recognition unit 21d of the camera unit 21, and a driving information detection unit 26 as a driving information detection means, etc. The vehicle control unit 22 acquires the driving environment of a predetermined range of the target route ahead of the host vehicle M based on the road map information around the target route set by the target route setting calculation unit 12c and the forward driving environment information recognized by the forward driving environment recognition unit 21d.
The driving information detection unit 26 is a collective term for various sensors that detect driving information of the host vehicle M necessary for autonomous driving, such as the vehicle speed (host vehicle speed), acceleration/deceleration, arrival time to the stop line, inter-vehicle distance between the host vehicle M and the preceding vehicle, and relative vehicle speed.

Furthermore, connected to the output side of the vehicle control unit 22 are a steering control unit 31 that drives the vehicle M along the target travel path, a brake control unit 32 that decelerates and stops the vehicle M by applying forced braking, an acceleration/deceleration control unit 33 that controls the vehicle speed of the vehicle M, and an alarm device 34 that issues an alarm to the driver according to the situation recognized based on the driving environment ahead.

The vehicle control calculation unit 22a performs predetermined control on the steering control unit 31, the brake control unit 32, and the acceleration/deceleration control unit 33, and automatically drives the host vehicle M along the target route on the road map set by the target route setting calculation unit 12c based on the positioning signal indicating the host vehicle position received by the GNSS receiver 13. At that time, the vehicle control calculation unit 22a performs well-known adaptive cruise control (ACC control) and active lane keep (ALK) control based on the forward driving environment recognized by the forward driving environment recognition unit 21d, and follows the preceding vehicle when a preceding vehicle is detected, and drives the host vehicle M along the driving lane at the first ACC set vehicle speed set by the driver with the speed limit of the road as the upper limit when a preceding vehicle is not detected.

The intersection detection unit 22b constantly detects whether or not a pair of intersections with an interval shorter than a predetermined interval exists within a predetermined range (e.g., 300 [m]) of the target route ahead of the vehicle M, based on the driving environment of a predetermined range of the target route ahead of the vehicle M acquired by the vehicle control unit 22. Specifically, the intersection detection unit 22b constantly detects whether or not a pair of intersections that satisfy the condition of formula (1) exists within a predetermined range (e.g., 300 [m]) of the target route ahead of the vehicle M.
V ² _ACC /2a _max > d...(1)
where V _ACC is the first ACC set vehicle speed [m/s] set by the driver etc., a _max is the deceleration of the automatic deceleration control [m/s ² ], and d is the distance [m] between two intersections.

When the intersection detection unit 22b detects a pair of intersections whose interval is shorter than a predetermined interval, the ACC set vehicle speed changing unit 22c changes the first ACC set vehicle speed set by the driver, etc. to a second ACC set vehicle speed. Specifically, when the intersection detection unit 22b detects a pair of intersections that satisfy formula (1), the ACC set vehicle speed changing unit 22c changes the first ACC set vehicle speed to the second ACC set vehicle speed calculated by formula (2).
√(d×2a _max )...(2)
If, after changing to the second ACC set vehicle speed, the intersection detection unit 22b no longer detects a pair of intersections whose interval is shorter than a predetermined interval, the ACC set vehicle speed change unit 22c changes the second ACC set vehicle speed to the first ACC set vehicle speed set by the driver, etc.

Here, the change control process of the ACC set vehicle speed will be explained in more detail with reference to FIG. 2. In the example of FIG. 2, the host vehicle M will be described as traveling straight through two intersections, a near intersection (hereinafter referred to as the "near intersection") 41 and a far intersection (hereinafter referred to as the "rear intersection") 42.

At the near intersection 41, a near traffic light (hereafter referred to as the "near traffic light") 41a and a near stop line (hereafter referred to as the "near stop line") 41b are installed, and at the far intersection 42, a far traffic light (hereafter referred to as the "rear traffic light") 42a and a far stop line (hereafter referred to as the "rear stop line") 42b are installed.

When the vehicle control unit 22 determines that the traffic light 41a at the upcoming intersection 41 allows the vehicle to proceed (green light or arrow signal light is on) based on the forward driving environment recognized by the forward driving environment recognition unit 21d of the camera unit 21, the vehicle control unit 22 controls the vehicle to pass through the upcoming intersection 41 at a first ACC set vehicle speed set by the driver or the like.

Then, when the vehicle control unit 22 determines that the rear traffic light 42a of the rear intersection 42 is not advancing (red light) based on the forward driving environment recognized by the forward driving environment recognition unit 21d of the camera unit 21, it controls the brake control unit 32 and the acceleration/deceleration control unit 33, etc. to perform deceleration control in order to stop before the rear stop line 42b. At this time, if the distance between the front intersection 41 and the rear intersection 42 is d [m], if this distance d [m] is shorter than a predetermined interval, sudden deceleration control that is not intended by the driver will be required, and the ride comfort will deteriorate. Note that the distance d [m] is the distance between the front intersection 41 and the rear intersection 42, but is not limited to this, and may be the distance between the front traffic light 41a and the rear traffic light 42a, or the distance between the front stop line 41b and the rear stop line 42b.

Here, the upper limit of the deceleration a _max [m/s ² ] of the automatic deceleration control is set in advance. The upper limit of the deceleration a _max [m/s ² ] is set within a range that does not deteriorate the riding comfort of the passengers, for example, to a value of about 0.3 to 0.4 G (2.94 to 3.92 [m/s ² ]).

When the first ACC set vehicle speed is set to V _ACC [m/s] by the driver or the like and the vehicle M is traveling at a speed of V _ACC [m/s], the distance that the vehicle M travels while continuing to decelerate at a deceleration rate a _max [m/ ^s2 ] until it comes to a stop can be calculated using equation (3).

∫(V _ACC -a _max t)dt...(3)
(However, the integration range is 0 to V _ACC /a _max )
By calculating the above formula (3), the distance traveled while traveling at a speed of V _ACC [m/s] and continuing to decelerate at a deceleration rate a _max [m/s ² ] until the vehicle stops is given by: V ² _ACC /2a _max [m].

That is, when the distance traveled before stopping, ^V2ACC / _{2amax [} m], is equal to or less than the distance d [m] between the near intersection 41 and the far intersection 42, the vehicle can decelerate and stop without deterioration of ride comfort. On the other hand, when the distance traveled before stopping _, ^V2ACC / _2amax [m], is longer than the distance d [m] between the near intersection 41 and the far intersection 42 (satisfying the condition of formula (1)), deceleration control must be performed beyond the upper limit of deceleration _amax [m/ ^s2 ], which deteriorates the ride comfort of passengers.

Therefore, when the intersection detection unit 22b detects a pair of intersections whose interval is shorter than a predetermined interval, the ACC set vehicle speed change unit 22c changes the first ACC set vehicle speed set by the driver or the like to a second ACC set vehicle speed calculated by formula (2).

The ACC set vehicle speed change control process will be described with reference to FIG. 3. The ACC set vehicle speed change control process in FIG. 3 is executed by the cruise control unit 22 at a predetermined calculation cycle when the vehicle is in automatic driving mode.

First, the driving control unit 22 acquires the driving environment within a predetermined range (e.g., 300 m) of the target route ahead of the vehicle M based on the road map information acquired by the road map information acquisition unit 12b and the forward driving environment (forward driving environment information) recognized by the forward driving environment recognition unit 21d of the camera unit 21 (step S1).

Based on the driving environment acquired in step S1, the driving control unit 22 determines whether or not a pair of intersections with a distance shorter than a predetermined distance has been detected within a predetermined range of the target route ahead of the vehicle M (step S2). The intersection detection unit 22b detects pairs of intersections with a distance shorter than a predetermined distance using the above-mentioned formula (1).

When the cruise control unit 22 determines that a pair of intersections with a distance shorter than a predetermined distance has been detected within a predetermined range of the target route ahead of the vehicle M, it changes the first ACC set vehicle speed to a second ACC set vehicle speed (step S3) and ends the process. The first ACC set vehicle speed is a vehicle speed set by the driver or the like, and the second ACC set vehicle speed is a vehicle speed calculated by the above-mentioned formula (2), and the second ACC set vehicle speed is slower than the first ACC set vehicle speed.

On the other hand, if the cruise control unit 22 determines that a pair of intersections with a distance shorter than the predetermined distance has not been detected within a predetermined range of the target route ahead of the vehicle M, it determines whether the vehicle speed has been changed to the second ACC set speed (step S4).

If the cruise control unit 22 determines that the vehicle speed has not been changed to the second ACC set speed, it ends the process.

On the other hand, if the cruise control unit 22 determines that the ACC set vehicle speed has been changed to the second ACC set vehicle speed, it changes the second ACC set vehicle speed to the first ACC set vehicle speed (step S5) and ends the process. In other words, when the ACC set vehicle speed has been changed to the second ACC set vehicle speed, if a set of intersections with an interval shorter than a predetermined interval is not detected within a predetermined range of the target route ahead of the vehicle M, the cruise control unit 22 returns the changed second ACC set vehicle speed to the original first ACC set vehicle speed.

By the above-described ACC set vehicle speed change control process, when the autonomous driving assistance system 1 detects a set of intersections with a distance shorter than a predetermined distance within a predetermined range of the target travel path ahead of the vehicle M, the autonomous driving assistance system 1 changes the first ACC set vehicle speed set by the driver or the like to a second ACC set vehicle speed that is slower than the first ACC set vehicle speed. As a result, the autonomous driving assistance system 1 does not need to perform sudden deceleration control to stop the vehicle even if the illumination color of the rear traffic light 42a of the rear intersection 42 is red (red light) when passing through the nearby intersection 41, and the ride comfort of the passengers can be improved. As a result, the autonomous driving assistance system 1 of this embodiment can suppress sudden deceleration control that is not intended by the driver.

Note that the steps in the flowcharts in this specification may be executed in different orders, multiple steps may be executed simultaneously, or the steps may be executed in different orders each time, provided that this does not contradict the nature of the steps.

The present invention is not limited to the above-described embodiment, and various modifications and alterations are possible without departing from the spirit and scope of the present invention.

1...Autonomous driving assistance system 11...Locator unit 12...Map locator calculation unit 12a...Vehicle position estimation calculation unit 12b...Road map information acquisition unit 12c...Target course setting calculation unit 13...GNSS receiver 14...Autonomous driving sensor 15...Destination information input device 16...High-precision road map database 21...Camera unit 21a...Main camera 21b...Sub-camera 21c...Image processing unit (IPU)
21d...Front driving environment recognition unit 22...Vehicle control unit 22a...Vehicle control calculation unit 22b...Intersection detection unit 22c...ACC set vehicle speed change unit 26...Driving information detection unit 31...Steering control unit 32...Brake control unit 33...Acceleration/deceleration control unit 34...Warning device 41...Front intersection 41a...Front traffic light 41b...Front stop line 42...Rear intersection 42a...Rear traffic light 42b...Rear stop line If...Imaging area

Claims (3)

An automatic driving assistance system that acquires a driving environment of a predetermined range of a target route ahead of a host vehicle based on road map information acquired by a road map information acquisition unit and driving environment information ahead of the host vehicle acquired by a camera unit,
an intersection detection unit that detects a set of intersections having an interval shorter than a predetermined interval within a predetermined range of the target route ahead of the host vehicle based on a driving environment within the predetermined range of the target route;
an ACC set vehicle speed changing unit that changes a first ACC set vehicle speed that has been set to a second ACC set vehicle speed that is slower than the first ACC set vehicle speed when the intersection detection unit detects a pair of intersections whose interval is shorter than the predetermined interval;
having
The intersection detection unit detects whether there is a pair of intersections spaced apart from each other at an interval shorter than the distance traveled by the vehicle, while traveling at the first ACC set vehicle speed, until the vehicle continues to decelerate at a preset upper limit of deceleration and stops . The intersection detection unit detects whether or not a pair of intersections that satisfy the following formula (1) is present within a predetermined range of the target route ahead of the host vehicle, based on a driving environment within a predetermined range of the target route,
The autonomous driving assistance system according to claim 1, characterized in that, when the intersection detection unit detects that a set of intersections that satisfies the following formula (1) exists within a predetermined range of the target travel route ahead of the vehicle, the ACC set vehicle speed change unit changes the first ACC set vehicle speed to the second ACC set vehicle speed calculated by the following formula (2):
V ² _ACC /2a _max > d...(1)
√(d×2a _max )...(2)
however,
V _ACC : First ACC set vehicle speed a _max : Deceleration rate of automatic deceleration control d: Distance between intersections. The automatic driving assistance system according to claim 1 or 2, characterized in that, when the ACC set vehicle speed has been changed to the second ACC set vehicle speed, the ACC set vehicle speed change unit changes the second ACC set vehicle speed to the first ACC set vehicle speed if the intersection detection unit detects that there is no pair of intersections whose interval is shorter than the specified interval.

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